Two young men and a male juvenile were still being questioned by police last night in connection with the fatal stabbing of 15-year-old Thomas Devlin from Somerton Road in north Belfast.
They were arrested on Thursday in a police follow-up operation after Thomas Devlin and two of his friends were attacked less than 200m from his home at about 11.30pm on Wednesday.
Thomas died from his injuries. One of his friends was injured, although not seriously, while his third companion escaped shocked but uninjured.
The PSNI said the current view of the attack was that it was random, while Gerry Kelly, the Sinn Féin Assembly member for North Belfast, said the killing bore "all the hallmarks" of a sectarian murder.
The SDLP raised the murder with the PSNI chief constable Hugh Orde yesterday. SDLP Assembly member Alex Attwood said afterwards it was for the police to make the call as to whether or not the murder was sectarian.
He expected police developments within 24 hours.
The PSNI said that two men wearing hoods, and walking a dog, who followed the three boys from an Esso garage only 500m from Thomas's home, were believed to have been responsible for the murder.
Thomas's parents, Jim Devlin and Penny Holloway, spoke again yesterday about their horror, distress and terrible sense of loss at the death of their son.
They again appealed for anyone with information about who killed Thomas to go directly to the police. Ms Holloway told the BBC that "Thomas was just such a shining beacon in our lives and it's gone and he's not going to come back.
"The people who killed Thomas have the capacity to kill a child again. They are not going to stop with Thomas, and somebody, somewhere knows who did it," she added.
Young people, many of them friends of Thomas Devlin, continued to leave flowers at the murder scene on Somerton Road yesterday.
Northern Secretary Peter Hain in a statement yesterday condemned the murder.